Multicircuit baroswitch for telemetering devices



Aug. 11, 1964 Y J. R. COSBY 3,144,531

MULTICIRCUIT BAROSWITCH FOR TELEMETERING DEVICES Filed June 22, 1960 2 Sheets-Sheet 2 T0 BLOCKING OSCILLATOR LOW 57 VOLTAGE CUT-DOWN FIG. 6

r BY ATTORNEY United States Patent 3,144,531 MULTHCIRCUIT BARG-SWITCH FER TELEMETERING DEVICES James R. Cosby, Towson, Md., assignor to The Bendix Corporation, Towson, Md., a corporation of Delaware Filed June 22, 1960, Ser. No. 37,951 7 Claims. (Cl. 290-83) Baroswitches for mass-produced telemetering devices, such as radiosondes, must be of exceedingly simple and low-cost, light-weight construction yet capable of efficiently performing the assigned functions. A type of baroswitch commonly used for radiosondes is one wherein a pivotally-mounted contact arm is driven by a diaphragm capsule across a printed circuit commutator supported on a light sheet metal frame, such as in the Talbott Patent No. 2,738,392. The problem in the present instance was to render such a switch capable of effectively performing its primary telemetering function over a wide altitude range, both on ascent and descent, and at preselected altitudes, condition circuitry for performing an additional function or functions, without requiring any substantial changes in the basic switch assembly. The Cosby and Wolf Patent No. 2,886,667 shows a multi-circuit baroswitch utilizing the basic parts of the Talbott baro, but in that case an additional contact arm and coacting parts are required; and the functions to be performed by the present switch involve problems utterly foreign to those which gave rise to the Cosby and Wolf switch.

An object of the present invention, therefore, is to adapt a simple type of baroswitch, which has become standardized in mass-produced radiosondes, to a wide range of telemetering at preselected altitudes, and in addition control one or more separate-function circuits to be cut in or out at preselected pressures or altitudes. In the example illustrated and described herein, the telemetering device is of the balloon-borne type, and the separate-function circuit is utilized to fire a balloon cut-down squib at a given altitude, the squib circuit incorporating an arming switch controlled by the arm ofthe baroswitch in a manner such as to require only a Simple insulating operation. By simply extending one of the contacts of the arming switch, it is caused to function as a telemetering-delay member.

The foregoing and other objects and advantages will become apparent in view of the following description taken in conjunction with the drawings wherein:

FIG. 1 is a plan view of a baroswitch in accordance with the invention, having diagrammatically associated therewith a simplified version of a pulse-generating oscillator for modulating the radio frequency transmitter "forming part of the telemetering circuit;

FIG. 2 is a View in side elevation of FIG. 1;

FIG. 3 is a view taken substantially on the line 33, FIG. 1;

FIG. 4 is a fragmentary plan view of the baroswitch of FIGS. 1, 2 and 3 in which a pair of coinmutators are arranged in superposed relation, to obtain a wide altitude range of telemetering, both on ascent and descent;

FIG. 5 is an end view of FIG. 4;

FIG. 6 is a top or active surface view of the lower commutator block of FIGS. 4 and 5; and

FIG. 7 is a view taken substantially on the line VII VII, FIG. 4.

ice

Referring to the drawings and first to FIGS. 1, 2 and 3, the baroswitch components are mounted on a frame member, generally indicated at 10, which is preferably in the form of a light-gauge sheet metal stamping, having therein an opening 11, adapted to receive a diaphragmtype aneroid capsule 12, which may be evacuated or filled with inert gas as is common practice in the art. The lefthand wall or diaphragm of the capsule (left as viewed in FIGS. 1 and 3) is adjustably anchored to the adjacent frame structure by means of a bracket 13 and threaded stud 14. The opposed wall or diaphragm is free to expand and contract and has connected thereto a boss 15, which at its outer free end is cavitated to receive the pointed end of a drive link 16, the opposite end of which has a slotted pivotal connection to the base portion 17' of a horseshoe-shaped ranging bracket 17, formed with a horizontally extending arm 18 (note FIG. 2), which is offset at its outer end and connected by means of a tension adjusting screw 19 with a movably-mounted switch member in the form of a baro arm 20. The bracket 17 and baro arm 20 are rigidly connected to one another for swiveling movement in unison on a pivot pin 21, journaled at its upper and lower pointed or beveled ends in the horizontally-extending portions of a main mounting bracket 22, the latter being fixed to the adjacent frame structure as by rivets 23. When the capsule 12 expands (decreasing atmospheric pressure), link 16, which is pivotally connected to the switch arm 20 through ranging bracket 17, exerts a driving thrust on said arm and swings it in a counterclockwise direction, or to the right as viewed in FIGS. 1 and 3, against the return force of a biasing spring 24. A screw 25 projects through the horizontal portions of the bracket 22 and threads into the baro frame; it provides an adjustment for the bearing thrust of the pin 21.

The baro arm forms part of a grounding circuit common to the individual circuits to be controlled; it may be grounded as at 26;, FIG. 1. The active end of the baro arm is provided with a pointed contact 27, slidable over the surface of a commutator block 28.

The commutator block 28 is adjustably mounted on the flat base portion of the frame 10. To accommodate such mounting, a bracket 29, FIG. 3, is secured to the under-surface of the commutator and slidably engages in an opening formed in the adjacent overlying frame wall. The one end of the bracket is bent at about a ninety-degree angle, to receive the threaded portion of an adjusting screw 30, encircled by a spring 31, which biases the bracket 29 to the left as viewed in FIG. 3. At its outer end the screw 30 is provided with a knurled discshaped head 32, frictionally held against rotation by a leaf spring type detent 33. By adjusting the screw 30, the commutator block 28 can be reset to determine its proper location with respect to the baro arm 20.

The foregoing parts represent standard construction more or less common to baroswitches for mass-produced radiosondes and form no part of the present invention other than in combination with structure to be described.

The commutator block 28 has fixed therein a series of terminals 34' to 42', inclusive, and the surface of the block is provided with a series of inlaid commutator segments 34 to 42, inclusive, which are connected to said terminals by means of inlaid conductors. In the present instance, the baroswitch was adapted for use in a socalled acousticsonde, in which signals of different fre- 51. In the acousticsonde, the output of the'oscillator is applied to a speaker and microphone system (not shown), which in turn acts through suitable amplifying circuitry to modulate a radio frequency transmitter, also not shown.

I A combined arming and telemetering delay switch comprises a bar or arm 52 of conductive material, such as brass or copper, which is'fixed at one end to the commutator block 28, from which point it is offset upwardly as viewed in FIG. 3, then extends a predetermined distance parallel to, and terminates in a free end spaced from, the active commutator surface. A terminal 52' projects from the anchored end of the bar and is connected in circuit with a balloon cut-down squib, diagrammatically indicated at 53 in FIG. 1. A leaf spring contact 54 has its. one end anchored to the commutator block at 55, from which point it is bent upwardly and sprung or tensioned in a direction to contact the top surface of the bar 52 when not separated therefrom by the free extremity of the baro arm 20, which rides on the arm 52 and is insulated from said arm, as indicated at 56. A convenient method of insulating the baro arm is to wrap it with insulating tape, although other methods may be found more expedient. The rear end of the spring contact 54 is provided with a terminal 54, FIG. 1, which is connected in circuit with the one contact 57 of a low voltage cut-down relay 57, the armature of which is normally closed against the opposed contact 57". Contact 57 is connected in circuit with commutator segments 41 and 42 across jumper 41" and terminals 41' and 42', The solenoid of this relay 57 is normally connected to an acousticsonde power-supply battery of, say 6 volts. Should the voltage of the battery drop below a required operational value, the relay will open and energize the balloon cut-down circuit in a manner to be described.

Operation of FIGS. 1, 2 and 3 As heretofore indicated, the baroswitch illustrated and described in FIGS. 1, 2 and 3 is adapted for use in an acousticsonde, which is carried aloft by a free balloon. When it attains a preselected altitude, determined by the effective length of the bar 52, the acousticsonde will begin to transmit signals to a radio receiver usually forming part of a ground station, which in addition may include a recorder and/or tracker, indicating the altitude and the position of the acousticsonde. The baroswitch is disarmed following assembly in the acousticsonde and remains disarmed up to some preselected altitude, to avoid possible premature firing of the squib 53, which might occur due to vibration or jarring during handling and preparation for flight and take-off. Disarming is accomplished through the medium of the spring 54, which is held spaced from and out of contact with the bar 52 by the insulated portion of the baro arm 20 until the latter has been driven by capsule 12 the distance of the spring length in a counterclockwise direction (decreasing pressure), as viewed in FIGS. 1 and 3. This amount of travel of the baro arm may represent an altitude of, say 10,000 feet, at which point the insulated portion of said arm clears the spring 54, and the latter contacts the bar 52. This arms the squib circuit, i.e. the circuit will remain open but is placed in a condition where it can be closed by (l) the baro contact 27 engaging either one of the segments 40 or 41, or (2) through the relay 57 4 should the battery voltage drop below a safe operational value.

As the balloon rises to an altitude of, for example 48,000 feet, the baro arm drops off the rod or shelf 52 and engages the contact 3%; and from then on as the balloon gains or loses altitude (assuming it remains at or above about 50,000 feet), the acousticsonde will transmit signals of difierent frequencies identifying the altitude. It will be noted that the segments 38, 37 and 36 are interspersed with segments 35 and 34 for repeated contact by the baroswitch. This is done to obtain a repetition of certain signals at the cruising altitude.

The acousticsonde balloon may ride at varying altitudes above the cut-down level over a certain period of time until, due to balloon leakage, change in atmospheric conditions or other causes, it begins its descent, which would normally be more or less gradual. When it drops to an altitude of, say 50,000 feet, the baro contact will engage the segment 42 and this will complete a circuit from the squib battery through the squib, wire 53, terminal 52', bar 512., spring 54, terminal 54', wires 53 and 42", segment 41, and baro arm 20 to the return side or ground, whereupon the squib will fire, freeing the acousticsonde from its balloon and opening a parachute, which will take over and permit the acousticsonde to drop relatively quickly to the ground surface. This is done to comply with air trafiic regulations which prohibit sounding balloons to float free below some given altitude. Should the squib fail to fire when the baro arm contact 27 is riding on segment 40, it will be given a second voltage shot when the said contact engages segment 41.

During this rapid descent, the baro contact 27 will ride on the segments 39 and 40, sending out a frequency indicative of the rapidly decreasing altitude.

If while the acousticsonde is in flight in the telemetering zone, the acousticsonde power battery voltage should require a multiple of circuits all of which are controlled by the use of a single baro arm and commutator.

FIGS. 4 to 7, Inclusive The baroswitch of FIGS. 4 to 7, inclusive, was adapted for a telemetering device known as the pulsonde. It, too, is carried aloft by a free balloon and sends out signals indicative of altitude. In this instance, however, the device signals from the time it leaves ground level all the way up to its highest altitude and return. Upon dropping to a preselected altitude at termination of the flight, the squib circuit comes into operation and releases the device from its balloon and a parachute takes over in the same manner as in the acousticsonde. Substantially the same type of arming circuit is used as in the acousticsonde, but since the signal-delay bar is not required, it is eliminated and substituted by an inlaid conductor 60, which coacts with a pro-stressed contact spring 61, functioning in the same manner as the spring 54 of the acousticsonde circuit.

In FIGS. 4-7, parts which correspond to like parts in FIGS. 1, 2 and 3 are given like reference numerals.

In the pulsonde, a double-deck commutator assembly made up of commutators 62 and 63 is utilized. This'saves space and renders it possible to use a standard baroswitch frame assembly for a wide range of altitudes. The upper commutator 62 is provided with a series of inlaid segments 64 to 68, inclusive, which together cover an altitude span of, for example, 43,000 feet, each segment covering a given increment of altitude. The respective segments are provided with wiring terminals 64' to 68, inclusive. The terminals 65' to 68', inclusive, are connected by way of inlaid conductors 69, 70, 71 and 72 with other resistor wiring terminals 69' to 72, inclusive. Since different altitudes are identified by signals of different frequencies, resistors 73 to 77, inclusive, are connected to the terminals provided therefor in a manner'such that the commutator segments are placed in series with the baro arm 20, when contact is made, and a relaxation or blocking oscillator, not shown, but which may be the same as that indicated at 51 in FIG. 1.

The lower commutator block 63 is provided with a series of segments 78 to 87, inclusive (note FIG. 6), provided with inner terminals 78' to 87, inclusive. Termin-als 79', 80', 81' and 83' to 87, inclusive, are connected by way of inlaid conductors 8894, with outer terminals 88-94'. The segment 82 is a balloon release or cutdown segment; when the baro arm contact engages this segment, the squibcirc uit is completed to ground by way of wire 95, leaf spring 61, inlaid conductor 60 on the upper commutator block 62, circuit wires 95 and 96, terminal 82', segment 82 and the baro arm 20. It will also be noted that the low voltage cut-down relay may also ground the squib circuit when its switch arm is released against contact 57'.

The segments 78-81 and 8387 are connected in series to the blocking oscillator through resistors 97 to 104, inclusive, the respective values of which are such as to produce altitude identifying signals of different frequencies as the baro arm contact Wipes the segments.

Operation of FIGS. 4 to 7, Inclusive During the initial period of the flight, the squib circuit will be armed at, say 15,000 feet, at which point the insulated portion of the baro arm will permit the spring contact 61 to engage the conductor 60. When the circuit is so armed, it will be placed in position for completion of the squib circuit and firing of the squib when the baro arm contact 27 engages the commutator segment 82, or should the voltage of the pulsonde power battery drop below its operational value. The baro arm will continue to ride on the top commutator until, for example, an elevation of 50,000 feet is attained, at which point it drops off of the top commutator block and its contact 27 rides on the surface of the bottom commutator block 63. As the pulsonde continues to increase in altitude, the baro arm will swing further in a counterclockwise direction and engage or wipe the commutator contacts 81 to 78, inclusive. When the maximum altitude is gained, or for some other reason the flight is terminated, the pulsonde will begin to drop more or less gradually until at, say 46,000 feet, the baro arm contact 27 engages the squib cut-down segment 82, whereupon the squib is fired, the balloon is freed, and the parachute takes over. The pulsonde now drops rapidly; however it will continue to send out signals until it again reaches ground level since the baro arm contact, during this portion of descent, successively engages commutator segments 83 to 87, inclusive.

Here, as in FIGS. 1, 2 and 3, a simple single contact arm baroswitch effectively accommodates a multiple of signal and associated function circuits.

What I claim is:

1. In a baroswitch for controlling a plurality of electrical circuits as a function of altitude including a telemetering circuit and a separate-function circuit which requires arming at a given altitude, a pressure-responsive device, a movably mounted baroswitch arm connected to said device to be driven thereby, a contact element carried by said arm, a commutator provided with a series of commutator segments adapted to be connected into said electrical circuits and located for wiping engagement by said contact element, certain of said segments being adapted to effect closure of a telemetering circuit and at least one other of said segments being adapted to effect closure of a separate-function circuit, and a combined arming and telemetering delay switch including an elongated conductor and coacting elongated cont-act member spring-biased towards closed position against said conductor, the arming switch being open as long as said contact member is held clear of said conductor, said arm being provided with an insulated portion'which during the initial part of its travel rides on said conductor and holds said contact member clear of the conductor, the latter being of a length to delay engagement of said baroswitch arm contact with said telemetering segments until a preselected altitude is attained such that said baroswitch arm contact can effect closure of said separate function circuit only when moving in a pressure increasing direction.

2. In a baroswitch for controlling a plurality of electrical circuits as a function of altitude including a telemetering circuit and a squib-firing circuit, a pressure-responsive device, a movably mounted switch arm connected to said device to be driven thereby, a contact element carried by said arm, a commutator provided with a series of signal segments and at least one squib-firing segment located for wiping engagement by said contact element, and a combined arming and telemetering delay switch adapted to be connected into said squib-firing circuit comprising an elongated bar of conductive material on which the switch arm rides during a portion of its travel in a pressure-decreasing direction, and a coacting elongated contact member spring-biased towards closed position against said bar, said switch arm being provided with an insulated portion which engages between said contact member and said bar and maintains the arming switch open, said insulated portion when clearing said contact member effecting closure of the arming switch and continuing to ride on said bar until the switch arm drops off and its contact element engages said telemetering segments.

3. In a baroswitch for controlling a telemetering circuit, a pressure-responsive device, a baroswitch arm connected to said device to be driven thereby, a contact element carried by said arm, a pair of first and second commutator blocks arranged in spaced superposed relation with the first of said blocks terminating short of the second block in a pressure-decreasing direction, the first block being provided with a series of telemetering signal segments covering a selected range of altitude for wiping engagement by said contact element as the baroswitch arm is driven in a pressure-decreasing direction and the second of said blocks being provided with a series of signal segments covering a range of altitude between minimum and maximum pressures, the baroswitch arm moving free of the first block onto the second block upon being driven beyond the termination point of the first block.

4. A baroswitch as claimed in claim 3 wherein a circuit for performing a function other than telemetering is provided and the second of said commutator blocks incorporates a segment for energizing said circuit upon contact therewith by said baroswitch arm contact at a predetermined altitude, and an arming switch is provided for said latter circuit which is controlled by said baroswitch arm.

5. In a baroswitch for controlling a telemetering circuit, a pressure-responsive device, a baroswitch arm connected to said device to be driven thereby, said arm being pivoted at its one extremity and carrying a contact element at its opposite extremity which is caused to travel in an arcuate path in one direction upon a decrease in pressure and in the opposite direction upon an increase in pressure, a pair of upper and lower commutator blocks arranged in spaced superposed relation with the upper block terminating short of the lower block in a pressure-decreasing direction, the upper block being provided with a series of telemetering segments covering a selected range of altitude for wiping engagement by said contact element as the baroswitch arm swings in a pressure-decreasing direction and the lower of said blocks being provided with a series of signal segments covering a range of altitude between minimum and maximum pressures, the contact element on the free extremity of the baroswitch arm clearing the upper block and dropping onto the lower block when the said arm has been-driven beyond the termination point of the upper block.

6. A baroswitch as claimed in claim 5 wherein there are provided at least two additional circuits for performing functions other than telemetering and an elongated switch member is carriedtby said upper block which is spring-biased toward closed position against a conductor on said upper block and said baroswitch arm has an insulated portion which during the initial travel of the arm moves between said elongated switch member and its coacting conductor and thereafter moves clear of said latter member, permitting it to close against its conductor, and said lower block is provided with a segment effective to close the other of said circuits when it is wiped by the baroswitch arm contact element as the latter travels in a pressure-decreasin g direction.

7. A 'baroswitch as set forth in claim 2 wherein said elongated bar of conductive material is elevated above the level of said commutator such that as said switch arm is moved in a pressure increasing direction with decreasing altitude, it returns under said elongated bar thereby contacting said squib-firing segment. 1

References Cited in the file of this patent UNITED STATES PATENTS 

3. IN A BAROSWITCH FOR CONTROLLING A TELEMETERING CIRCUIT, A PRESSURE-RESPONSIVE DEVICE, A BAROSWITCH ARM CONNECTED TO SAID DEVICE TO BE DRIVEN THEREBY, A CONTACT ELEMENT CARRIED BY SAID ARM, A PAIR OF FIRST AND SECOND COMMUTATOR BLOCKS ARRANGED IN SPACED SUPERPOSED RELATION WITH THE FIRST OF SAID BLOCKS TERMINATING SHORT OF THE SECOND BLOCK IN A PRESSURE-DECREASING DIRECTION, THE FIRST BLOCK BEING PROVIDED WITH A SERIES OF TELEMETERING SIGNAL SEGMENTS COVERING A SELECTED RANGE OF ALTITUDE FOR WIPING ENGAGEMENT BY SAID CONTACT ELEMENT AS THE BAROSWITCH ARM IS DRIVEN IN A PRESSURE-DECREASING DIRECTION AND THE SECOND OF SAID BLOCKS BEING PROVIDED WITH A SERIES OF SIGNAL SEGMENTS COVERING A RANGE OF ALTITUDE BETWEEN MINIMUM AND MAXIMUM PRESSURES, THE BAROSWITCH ARM MOVING FREE 